* Dialga's high catch rate: While Dialga is a legendary Pokémon, it actually has a relatively high catch rate (45). This means you have a reasonable chance of catching it even without a Master Ball, especially if you weaken it and use other techniques.
* Master Balls are rare: Master Balls are incredibly rare items. It's generally advised to save them for truly difficult or important catches, rather than using them on a Pokémon you have a good chance of capturing with other methods.
How to catch Dialga:
1. Weaken Dialga: Reduce its HP as much as possible, ideally to the red health zone.
2. Status ailments: Inflict status ailments like Sleep, Freeze, or Paralysis. This significantly increases your chances of catching it.
3. Use Ultra Balls or Timer Balls: These are stronger Poké Balls that increase your chances of capture. Timer Balls are especially effective if the battle lasts long.
4. Consider using a "Catch Combo" strategy: In some games, you can increase your catch rate by catching other Pokémon in the same area before encountering Dialga.
Remember: Catching Dialga is a bit of a challenge, but with the right tactics and a bit of luck, you can definitely succeed without resorting to a Master Ball.